Compensating center



Jan. 7, 1930.

2 Shee'cs-Sheec m. m f v m. W. h. I.. l1 w E, n v m .t

ATTOR EK Patented Jan. 7, 1930- ;UNITED STATES ERNEST scHNELLE, or ROCHESTER., NEW vom:

COMPENSATING CENTER Application mea march 19, 1923. serial No. 626,240.

This and other objects of this invention will be fully illustrated in the drawings, described -in the specification and pointed out in the claims at the end thereof.

In the accompanying drawings, Figure 1 is a perspective view of a portion of a lathe withone of my improved compensating centers shown in the headstock and one of my improved anti-friction centers inl the tailstock of the lathe.

Figure 2 is a vertical longitudinal section of my improved compensating center.

Figure 3 shows a modification of my Compensating center provided with ball bearings.

In the drawings like reference numerals indicate like parts.

In the drawings, reference numeral 1 indicates the shank of the center which is formed by a hollow sleeve. In this sleeve is mounted the' spindle 2V provided with the center point 3 `on the forward end thereof; The sleeve 1 is'tapered rearwardly and at the rear end is recessed as indicated at 4 which 'recess is threaded with a female thread. In this recess is provided an adjusting screw 5 that is provided with a male thread thatengages with the female thread of the recess'. This screw has a reduced shank 6 which is provided with flat sides as indicated at 7 and 8 by which it may be turned by a wrench to adjust it forward and back in the recess. A cap 9 is provided, the forward end of which is reduced as indicated at 10 and which is also' threaded with a male thread to 'engage with .the female thread of the recess 4 and close the rear end of the sleeve 1. f The screw 5 hasa' central opening therein throughlwhich t-he center may be oiled. The spindle 2l is provided with grooves for carrying the oil therein.

Between the adjusting screw 5and the rear end of the spindle 2 of the center point is provided the spring 11 which is made excessively heavy and stiff so that it will yield only E under great pressure but when the pressure is applied it will yield as a spring should with -proper elasticlty. The forward end of the sleeve 1 is expanded as indicatedat 12 and is provided witha recess 13 in which is contained the head 14 of the center, the recess and the head being cylindrical in shape so that the head canturn in the recess and move back and forth therein. A packing groove 15 is provided in the head in which is contained any suitable packing to close the joint between the head and the sleeve.

The shank 2 is recessed as indicated at y16 and the sleeve 1 is recessed as indicated at 17 land when these recesses are in line a pin 18 is driven through the opening formed thereby which locks tleshank and sleeve together. The recess in the sleeve is semi-circular and'A the pin is securely -held in place thereby. The

recess of the shank is elongated and permits I wardly under great pressureand inthe revcess 13 suicient clearance isprovided bei85.v

tween the head of the center point and the" sleeve,- to permit of ample movement to take care of 'any expansion in the stock that is be# ing turned in the lathe;

As shown in Figure 1 the compensating 90" center is mounted in Athe headstock of the lathe and turns with the headstock and'withl the stock 20 that is being turned in the lathe. As heavy cuts are made on the stock 20'the stock heats up and expands and the Bureau. of Standards is said to' have calculated that this expansion causes a pressure of over 5800 pounds for every cubic inch of machined' steel when its temperatureincreases by 30 F.

* The center accommodates itself to this expanv expansion of the stock 20 on the centers in both the head stock and the tailstock will not destroy the centers or impair their accuracy. It will also be understood that the center inthe tailstock is an anti-friction or ball bearing center and the spring 11 in my improved compensating center in the headstock will protect the part in the anti-friction center in the tailstock from excessive pressure.

In Figures 3, 4 and 5 I have shown these centers provided with ball bearings so that the compensating center can be used inthe tailstock of the lathe.

In Figure 3 reference numeral 25 indicates the sleeve of the center and reference numeral 26 indicates .the head of the-center that is formed onthe outer end of the shank 27 as an integral part thereof. The inside' diameter of the forward portion of the sleeve-25 is enlarged to form a chamber in which the shank 27 is supported by the ball races 28 and 29 near the head of the shank and the ball races 30 and 31 at the rear of the shank. Suit- 'able balls between these two pair of ball races provide the anti-friction bearings which rotatably support the front and rear of the shank in the enlarged chamber ofthe sleeve. The rear end of the shank is reduced in diameter and the shoulder 32 formed thereby transmits the end thrust of the shank against the ball races 30 and 31 andthe anti-friction thrust bearing formed by them. Surrounding the shank 27 and suitably fastened thereto if only by a pressed fit is a spacing sleeve 33 which separates the anti-frictlon thrust bearing at the rear end of the shank from the anti-friction radial bearing near the front end ofthe shank. The ball race 29 of the radial anti-friction bearing is fastened into the inside of the chamber as for example by means of a pressedft so that after the anti-friction bearings both at the front and rear ofthe shank have been put in place and the assembly forced into the chamber, the shank is held against endwise movement in the chamber by the pressed t or other suitable fastening means between the ball race 29 and the inside of the chamber, and a similar fastening means between the shank and the spacing sleeve 32.

- Sup orting the race 31 is provided the spring lco `with the female thread `in the recess 37 on the sleeve. The screw 36 has a reduced shank 37 which is provided with Hat sides as indicated at 38 and 39 by which it may be turned by a wrench to adjust it forward and back in the recess. A cap 40 is provided, the forward end of which is reduced and is threadedwith a male thread to engage with the female thread of the recess 37 and close the rear end of the sleeve 25.

I claim:

1. A compensating center comprising 'a sleeve, a shank mounted within said sleeve, a head on the outer end of said shank and projecting from said sleeve, a yielding cushioning member located within said sleeve and acting against the inner end of said shank, means for holding said cushioning member a ainst endwise movement in the direction o expansion of said cushioning member and a flange overhanging the portion of said shank that projects from said sleeve thus providing a covered annular recess between the end of said sleeve and the back of said head for.the movement of said head toward said sleeve.

2. A compensating center com rising a sleeve, a shank mounted within sai sleeve, a head on the outer end of said shank and projecting from said sleeve, a yielding cushioning member located within said sleeve and acting against the inner end of said shank, and

an anti-friction bearing located between said shank'and said sleeve to allow the rotation of said shank in front of said yielding cushioning member and to prevent an endwise movement of said shank out of said sleeve.

3. Acompensatingcenter pointfer head and 'tail stocks com rising a sleeve adapted to be frictionally he d in place against endwise movement and rotation within a head or tail.

stock, a shank within said sleeve, a head formed on said shank, an adjustable plig in lng said. sleeve and a yielding member yie only under extreme pressures inter osed between said shank and said plug to old said said shank in the opposite direction, and

means for holding said shank against movement in the opposite direction.

4. A compensating center point for head` and tail stocks comprising a sleeve adapted to be frictionally held in place against endwise movement and rotation within a head-or tail stock, a shank within said sleeve, a head formed on said shank, an adjustable plug in lll said sleeve and a yielding member yielding only under extreme pressures interposed between said shank and said plug to hold said shank against endwise movement toward said j plug except under extreme pressures, sa1dplug being adapted to constantly hold said yielding member against the end of said shank, and normally hold said shank against said shank in the o means for holding said shank endwise movement toward the rear of said sleeve without exerting any pressure against posite direction, and means for holding said shank against movement in the opposite directionantifriction bearings rotatabl supporting said shank within said sleeve etween said yielding member and said means for holding said shank against movement away from said yielding member.

5. A compensating center comprising a fixed supporting member, a shank mounted to rotate within saidsupporting member, a head formed on the outer ,end of said shank, and projecting from said supporting member, an anti-friction bearing supporting said shank within said supporting member, a cushioning member within said supporting member normally holding said shank agalnst movement in one direction but yieldingly resisting an overload pressure against sa1d shank and means cooperating with said antifriction bearing to hold said shank against'endwise movement in the opposite direction and 4free rom the end thrust of said cushioning mem- 6. A compensating center comprising a supporting member having a chamber formed at one end thereof, a shank located within saidchamber and rotatably and slidably supported in said chamber, a cushioning member located within said chamber and normally holding said shank against movement into said chamber without exertin anypressure against said shank to allow said shank to rotate freely within said 'anti-friction bearing, said cushioning memberbeing adapted to antifriction' bearin and mounted to freely rotate within sai chamber member yieldingly resisting the endwise movement durin a free rotatlon of said splndle within said c iamber and means cooperating with said antiriction bearing for lock-r ing said spindle against endwise movement out of said chamber.

a cushioning e 9. In a compensating center, the combina-` tion of a stationary support, a 'chamber formed in one end of said support, a shank rotatably su ported in said chamber, a cush-r ioning mem er located within said chamber and yieldingly resisting the endwise movement of said shank due to pressure against said shank and means for holding said shank against endwise movement within said chamber and free from the expansive pressure of said cushioning member to allow said shank r to rotate freel -wi'thin said shank before pressure is app ied against said shank.

In testimony whereof I atlx my signature.

ERNEST E. SCHNELLE.

loo

yield to excessive pressureagainst said shank and allow said shank to move endwi'se in said anti-frlctlon bearing 1n one dlrectlon and movement in said anti-friction bearing in the opposite direction.

against` endwise Y compensating center comprising a fixed supporting member, a chamber formed in one end of said sup ortinv member, a shank rotatably supporte center shank and projecting from said chamber, a cushioning member within said chamber and Y means intermediate of said head and said cushioning membery for normally in sald. chamber, a point carried by the outer end of said holding s aid Y shank free from the end thrust offsaidcushsaid means allowing the movement o f said ioning member and-against endwise movement away from said cushioning member,.

shank toward` said cushioning member y to .y yieldingly resist an overload pressure against y the center point.' 8; In a compensatingv center, the combination of a shank adapted to be mounted in a socket with one end thereof, a chamberf ",'Hmformedinltle other end of said shank an antifriaiqn. bem'g spindle suppbrtaibyggid 

